The following Patent Document 1 discloses a golf club set aiming at obtaining the struck ball with proper backspin commensurate with to the club number of the respective club. This golf club set is composed of golf clubs whose loft angles are increased as the club number becomes increased. And the score lines or grooves formed in the ball striking face of the respective golf club are configured such that the angle of the corner formed between the ball striking face and an inclined surface of the groove is gradually decreased as the club number becomes increased, wherein the angle is 90 degrees in the pitching wedge.
The following Patent Document 2 discloses an iron golf club set aiming at providing the iron golf club set with which it is easy to stop the golf ball when making a short-distance approach shot by using an iron club whose club number is more than that of a sand wedge, and it is easy to obtain a stable trajectory and a proper distance when making a full shot by using an iron club whose club number is smaller than that of a sand wedge. In the Patent Document 2, it is suggested that the groove edges of the score lines (grooves) of the sand wedge are rounded by a radius of 0.1 mm, and the groove edges of the score lines (grooves) of the rest of the clubs from 5-iron to the approach wedge are rounded by a radius of 0.3 mm.
Patent Document 1:
Japanese Patent Application Publication No. H09-192274
Patent Document 2:
Japanese Patent Application Publication No. 2007-007181